Combine vinegar, sugar, salt, mustard seeds, coriander seeds and dill seeds in a heatproof bowl. Add hot water and stir until sugar dissolves and liquid is clear. Cool to room temperature.
Place cucumbers, garlic and dill in a large bowl. Toss to combine. Pour brine over all and turn to coat cucumbers. Cover them with a plate to weigh them down and keep them covered in brine. Cover bowl with plastic wrap and refrigerate overnight, stirring once or twice. Transfer to an airtight container and store for up to two weeks.
Recipe by practical preparedness at https://www.practicalpreparedness.net/homemade-refrigerator-dill-pickles.html